Add support for extended tooltips....

chrome/browser/resources/new_new_tab.js

 
 // Helpers
 
 function $(id) {
   return document.getElementById(id);
 }
 
 // TODO(arv): Remove these when classList is available in HTML5.
 // https://bugs.webkit.org/show_bug.cgi?id=20709
 function hasClass(el, name) {
@@ skipping 173 matching lines @@
         'unpinthumbnailtooltip' : 'pinthumbnailtooltip');
     t.querySelector('.remove').title =
         localStrings.getString('removethumbnailtooltip');
 
     // There was some concern that a malformed malicious URL could cause an XSS
     // attack but setting style.backgroundImage = 'url(javascript:...)' does
     // not execute the JavaScript in WebKit.
     t.querySelector('.thumbnail-wrapper').style.backgroundImage =
         'url("chrome://thumb/' + d.url + '")';
     var titleDiv = t.querySelector('.title > div');
-    titleDiv.title = titleDiv.textContent = d.title;
+    titleDiv.xtitle = titleDiv.textContent = d.title;
     titleDiv.style.backgroundImage = 'url("chrome://favicon/' + d.url + '")';
     titleDiv.dir = d.direction;
   }
 }
 
 /**
  * Calls chrome.send with a callback and restores the original afterwards.
  */
 function chromeSend(name, params, callbackName, callback) {
   var old = global[callbackName];
@@ skipping 840 matching lines @@
   optionMenu.hide();
 }
 
 window.addEventListener('blur', hideAllMenus);
 window.addEventListener('keydown', function(e) {
   if (e.keyIdentifier == 'Alt' || e.keyIdentifier == 'Meta') {
     hideAllMenus();
   }
 }, true);
 
+// Tooltip for elements that have text that overflows.
+document.addEventListener('mouseover', function(e) {
+  var el = findAncestor(e.target, function(el) {
+    return el.xtitle;
+  });
+  if (el && el.xtitle != el.title) {
+    if (el.scrollWidth > el.clientWidth) {
+      el.title = el.xtitle;
+    } else {
+      el.title = '';
+    }
+  }
+});
+
 // DnD
 
 var dnd = {
   currentOverItem: null,
   dragItem: null,
   startX: 0,
   startY: 0,
   startScreenX: 0,
   startScreenY: 0,
   dragEndTimer: null,
@@ skipping 105 matching lines @@
     el.addEventListener('dragover', bind(this.handleDragOver, this));
     el.addEventListener('dragleave', bind(this.handleDragLeave, this));
     el.addEventListener('drop', bind(this.handleDrop, this));
     el.addEventListener('dragend', bind(this.handleDragEnd, this));
     el.addEventListener('drag', bind(this.handleDrag, this));
     el.addEventListener('mousedown', bind(this.handleMouseDown, this));
   }
 };
 
 dnd.init();